Gangrenous pneumonia, ovine respiratory complex and visceral form of caseous lymphadenitis: Relevance in lower respiratory tract disorders of adult sheep

'Numerous disorders affect the lower respiratory tract of adult sheep, including Maedi Visna, ovine pulmonary adenocarcinoma and verminous pneumonias as reported elsewhere in this special issue. Herein we examine gangrenous pneumonia, ovine respiratory complex (ORC) and the visceral form of caseous lymphadenitis (CLA). Gangrenous pneumonia is a pulmonary infection commonly caused by inhalation of foreign materials, producing inflammation and necrosis of the lung parenchyma. ORC is a complex disease process involving a range of host-pathogen-environment interactions, where host immunological and physiological mechanisms interact with multiple etiological agents including bacteria, plus environmental factors or stressors. Visceral form of CLA commonly causes lesions in mediastinal lymph nodes and lung parenchyma, producing respiratory clinical signs, particularly the coughing that is responsible for transmission of the disease by aerosol. The economic relevance, etiological, clinical and pathological findings of these diseases are reviewed.